Peptide composition

Abstract

The present invention provides a peptide composition that can achieve both excellent storage stability and transparency. The peptide composition of the present invention includes: a self-assembling peptide; a buffering agent having a pKa of 3.5 or more and less than 7.5 and containing one or more nitrogen atoms; and water, and has a pH of from 4.5 to 6.6.

The invention claimed is: 
     
       1. A peptide composition having a pH of from 4.5 to 6.6, the peptide composition comprising:
 a self-assembling peptide having a C-terminus comprising an amide group, wherein a total charge of amino acid residues contained in the self-assembling peptide is more than 0 and +3 or less, and an amino acid at the C-terminus of the self-assembling peptide comprises a basic amino acid; 
 a buffering agent having a pKa of 3.5 or more and less than 7.5 and comprising histidine, thiamine nitrate, pyridine, bis-Tris, and/or N-methylmorpholine; and 
 water. 
 
     
     
       2. The peptide composition according to  claim 1 , wherein the self-assembling peptide has the following amino acid sequence, with the amide group at the C-terminus:
 a 1  b 1 c 1 b 2 a 2 b 3 db 4 a 3 b 5 c 2 b 6 a 4    
 
       wherein:
 a 1  to a 4  each represent a basic amino acid residue, 
 b 1  to b 6  each represent an uncharged polar amino acid residue and/or a hydrophobic amino acid residue, provided that at least five thereof each represent a hydrophobic amino acid residue, 
 c 1  and c 2  each represent an acidic amino acid residue, and 
 d represents a hydrophobic amino acid residue. 
 
     
     
       3. The peptide composition according to  claim 2 , wherein the amino acid sequence is selected from the group consisting of SEQ ID NOs: 1-4. 
     
     
       4. The peptide composition according to  claim 1 , wherein:
 a concentration of the buffering agent is in the range of from 1 mM to 100 mM, and 
 a concentration of the self-assembling peptide is in the range of from 0.01 w/w % to 10 w/w %. 
 
     
     
       5. The peptide composition according to  claim 4 , wherein:
 a concentration of the buffering agent is in the range of from 5 mM to 43 mM, and 
 a concentration of the self-assembling peptide is in the range of from 0.5 w/w % to 2.5 w/w %.